The present invention relates generally to a combination pump and motor adapted for operation by compressed air, and more particularly, to a form of air operated pump and motor, which is particularly adapted for use in circulating washing fluid such as solvent or the like where a source of compressed air is readily available.
In apparatus such as washers for parts, tools and the like, including those disclosed and claimed in U.S. Pat. No. 3,522,814, for example, and in U.S. Pat. No. 4,462,415, small electric motors are used to operate pumps for withdrawing solvent from a receptacle such as a drum or specially contoured container. The pump then circulates the solvent from the reservoir through a hose or the like into a sink area where the liquid flow may be directed onto parts or the like being washed and returned from there to the reservoir. In some case, filters may be provided to remove contaminants from the solvent.
While electric motors have a number of advantages for this purpose, there are certain advantages to air operated motors which may make them more attractive for this application. Assuming that a source of compressed air is available to operate a motor, compressed air has certain advantages over electric motors, including the total elimination of a fire hazard resulting from sparks incident to electrical short circuits and the like.
Air operated motors are not normally susceptible of overheating even when intentionally stopped, for example. Consequently, motors such as this do not burn out and are not the subject of safety hazards caused by undue temperatures which may cause solvent flashing or even fire or explosion.
Still further, it is often desired to provide a variable pumping rate and/or discharge pressure from the pump in question. While variable speed electric motors are known, these ordinarily require control circuits which make them much more expensive than counterpart single speed motors.
On the other hand, it is a very simple matter to adjust the speed of an air operated motor, simple by manipulating a flow rate or pressure control valve for the supply of air to reduce the volume and/or pressure of the air being fed to the motor.
While heretofore known air operated motors serving to actuate liquid pumps have possessed the foregoing and other advantages, a number of them have possessed certain disadvantages, including air flow paths leading to noisy operation, lack of easy controllability, noisy air discharge, and difficulty of adaption to varying lift heights and the like. Still other such motors have required parts that were somewhat difficult to fabricate and assemble, raising their cost above a minimum which would make them desirable for reliable operation at minimum cost.
According to the invention, an air operated pump and motor is provided wherein a simplified combination rotor and housing construction is featured and wherein the impeller of the pump may be spaced apart from the rotor of the motor by any desirable length.
In view of the failure of the prior art to provide a pump and motor having the advantages and characteristics desired for certain applications, including parts washers and other fluid pumps, it is an object of the present invention to provide an improved air operated pump and motor.
Another object of the invention is to provide an air operated pump and motor having a particular form of air operated turbine assembly formed by combination of a rotor having a plurality of radial vanes or blades positioned on an imperforate carrier having a series of axially extending discharge ports located near its inner diameter and lying axially opposite, and preferably radially inwardly from, the outlet ports for the rotor chamber.
Another object of the invention is to provide a pump construction which includes a rotor assembly disposed in a housing and serving to subdivide the interior of the housing into primary and secondary air chambers, and wherein the rotor includes a vented hub section, with the chamber also including closely spaced apart inner and outer covers providing an air diffuser with a peripheral outlet communicating with the secondary air chamber.
Another object of the invention is to provide a pump and motor wherein the rotor and pump impeller assemblies are disposed on a common shaft and spaced axially apart from each other, and are retained in this relation by a rigid sleeve assembly which may be varied in length for various pump applications without the requirement that other changes be made to the motor.
Another object of the invention is to provide an air operated pump and motor which includes an impeller in a lower chamber with peripheral inlets, one or more volutes directing fluid flow to an upwardly directed passage extending from the volute area to the pump outlet.
The foregoing and other objects and advantages of the invention are achieved in practice by providing a combination air operated pump and motor having a rotor head portion with an imperforate blade carrier affixed by a spider to a drive shaft hub and disposed in a housing which the rotor subdivides into primary and secondary air chambers, and wherein the rotor head also includes inner and outer spaced apart covers which provide an air diffuser with a peripheral outlet; the pump includes an impeller disposed in a lower housing and driven by a shaft affixed to the rotor.
The exact manner in which these and other inherent objects of the invention are achieved in practice will become more clearly apparent when reference is made to the following detailed description of the preferred embodiments of the invention set forth by way of example, and shown in the accompanying drawings, in which like reference numbers indicate corresponding parts throughout.